JPH0581867B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an in-circuit tester used for determining the quality of a mounted board, and particularly to an in-circuit tester that uses a fixture equipped with a probe pin as a measuring jig for a mounted board. 2. Description of the Related Art Conventionally, an in-circuit tester has been used to determine the quality of a mounted board, that is, a printed circuit board to which a large number of electrical components are soldered, in order to measure the electrical characteristics of those components. There are two types of in-circuit testers: press type and vacuum type, depending on the method of fixing the mounting board to the tester during measurement. In the press type, as shown in FIG. 5, a mounting board 12 having an electrical component 10 etc. is mounted on a fixture 1 with a plurality of probe pins 14, which serve as an inspection jig.
6, a press plate (not shown) having a plurality of presser bars 18 projecting downward is lowered from above to clamp and fix. At this time, it is originally necessary to bring the tips of each probe pin 14 into contact with the leads 20 and the like protruding from the main body of the electrical component 10.
However, as shown in FIG.
24 and 26, and each independent pattern is wired so that a plurality of parts can be contacted, so in reality, each independent pattern has one place, for example, a lead hole at one end or in the middle, and a lead hole around it. It is sufficient to determine the measurement land 28 consisting of the pattern as the inspection point, and erect one probe pin 14 that contacts the independent pattern with appropriate pressure only there. Usually, the wiring pattern on the board is composed of a large number of independent patterns, and therefore, a correspondingly large number of probe pins are required. Note that 30 in the figure is a positioning guide pin 3 that protrudes vertically from a mounting base plate (not shown) and is inserted into holes provided at each of the four corners of the mounting board 12 and fixture 16.
2 is a lead wire that electrically connects each probe pin 14 to the measurement section of the main body and transmits measured information. In addition, in the vacuum type, the mounting board is sucked onto a fixture with probe pins and fixed thereon. Therefore, in order to actually measure the electrical characteristics of each component such as a resistor, capacitor, or coil, it is necessary to measure the electrical characteristics of each component, such as a resistor, capacitor, coil, etc., by connecting the measuring section of the in-circuit tester to each channel connected to the probe pins of the components via a multiplexer. By passing a measurement current or applying a measurement voltage to each component, the values of their resistance (R), capacitance (C), inductance (L), etc. are obtained. Note that the object to be measured is not limited to general electrical parts, but can be anything that generates a voltage, so that shorts between independent patterns, open states, etc. are the same as in general testers. Problems to be Solved by the Invention However, such an in-circuit tester does not have a function of determining poor contact between the mounting board to be tested and the fixture, that is, whether the contact state of the tip of the probe pin with the measurement land is good or bad.
Therefore, users have combined the existing functions of the in-circuit tester to determine the contact failure of the probe pin. For example, in the table showing the measurement status and judgment results regarding the electrical characteristics of each part displayed on the screen, the judgment results are outside the GOOD range.
Step indicating NG (NO GOOD) such as OVER (horizontal column indicating measurement status and judgment result for each part)
If there is, other probe pin numbers using the same H-PIN (probe pin that contacts the signal source side of the component) or L-PIN (probe pin that contacts the measurement side of the component) of that step Search for the step, and if there is an OVER judgment for the step as shown in Table 1 below, the H-PIN1
It was assumed that the contact was defective, and as shown in Table 2, if there was a GOOD judgment for the step, it was assumed that the R3 component itself was defective. In each table, NAMER1 to R4 indicate each component, and mode R indicates resistance measurement.

【table】

[Table] In addition, in order to make more accurate judgments, we conduct a pin search for the probe pins of steps that indicate NG, and test the parts by measuring their electrical characteristics with a general tester. Ta. Note that pin search is an inspection to check the contact condition of the probe pin installed on the fixture and the presence or absence of breakage of the lead wire connected to it. By doing so, if there is a defect in any of them, no display will appear on the screen, so it can be seen that there is a contact failure in the probe pin or a break in the lead wire. However, these judgments cannot be made without specialized knowledge, and since they are made by humans, there is a possibility of erroneous judgments. Furthermore, since there are many work steps, it is time consuming and burdensome. The present invention has been made in view of these conventional problems, and provides a probe that can quickly and accurately determine the quality of the probe pin contact with the measurement land of the board to be tested. An object of the present invention is to provide an in-circuit tester having a pin contact defect determination function. Means for Solving the Problems Means for achieving the above object will be explained below using FIG. 1 which clearly shows the present invention. This in-circuit tester, which has a probe pin contact failure determination function, fixes the mounted board to be tested on the fixture, and attaches each probe pin attached to the fixture to each measurement land to which the leads of each component mounted on the board connect. An in-circuit tester 56 that measures the electrical characteristics of each part by contacting the parts and inspects the quality of each part.
Then, through these inspections, the probe pin used to measure the component determined to be defective is specified, and the specified probe pin is shared to measure the electrical characteristics of other components used for measurement, and the defectiveness of the component is determined. A component inspection means 58 for inspecting parts using a designated pin, and a defective parts number counting means 60 for counting the number of defective parts that share the designated probe pin, and when the count of defective parts reaches a predetermined value, the designated probe pin is detected as having a contact failure. A contact failure pin determining means 62 is provided. Operation With the configuration as described above, it is possible to first test the quality of each component mounted on the mounting board to be tested using the conventional testing function. The parts determined to be defective through these inspections include those in which there is no actual defect in the parts themselves, but which were measured with the pins in a state of poor contact. Therefore, in order to determine which probe pin has a defective contact state, the specified pin used component inspection means 58 specifies the probe pin used to measure the component determined to be defective, and the specified probe pin is shared for measurement. The electrical characteristics of other components used, that is, all components connected to the same independent pattern, are measured and the quality of these components is inspected. Next, the number of defective parts counting means 60 counts the number of defective parts that share the designated probe pin. Next, the defective contact pin determining means 62 determines that the designated probe pin has a defective contact when the count of defective parts reaches a predetermined value, for example 2. Because,
If the count number of a defective component is 1, it cannot be determined whether there is a defect in the component itself or a poor contact with the probe pin, so unless there are two or more defective components that are connected to the same independent pattern and share the designated probe pin. This is because it cannot be determined that the designated probe pin has poor contact. Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. FIG. 2 is a block diagram showing an in-circuit tester having a probe pin contact failure determination function to which the present invention is applied. In the figure, reference numeral 34 indicates a large number of probe pins provided on a fixture for fixing a mounting board to be inspected, and reference numeral 36 indicates a multiplexer interposed in a channel 38 that connects the probe pins 34 and the measurement section of the main body. These probe pins 3
4 are brought into contact with corresponding measurement lands of independent patterns on the mounting board. Furthermore, by arbitrarily selecting and switching the multiplexer 36 during measurement, the measuring section and each probe pin 34 can be turned on and off as appropriate. Further, 40 is equipped with a CPU that performs necessary processing to measure the electrical characteristics of each component mounted on the mounting board and to inspect the quality of each component itself and the contact state of each probe pin 34. It is a computing device.
Further, 42 receives an output from the device 40 and displays a display device such as a CRT that displays the probe pin 34 having a poor contact; 44 also receives an output from the device 40;
A dot to record the probe pin 34 with poor contact.
It is a recording device such as a printer. Note that in order to know which probe pins 34 have poor contact, it is sufficient to have a display device 42 that can easily use a screen, and the recording device 44 is not necessarily required. For example, the arithmetic device 40 equipped with this CPU has
CPU (central processing unit) 46, ROM (read-only memory) 48, RAM (read-writable memory)
50, an input/output port 52, a bus line 54, and the like.
The CPU 46 corresponds to the central brain of a microcomputer, and according to instructions from the program, controls the entire system, performs arithmetic and logical operations, and temporarily stores the results. or,
It also controls peripheral devices. ROM
48 stores a control program for controlling the entire in-circuit tester, a component and probe pin contact state determination processing program, and the like.
Further, the RAM 50 stores input data obtained by measuring the electrical characteristics of each component, data of calculation results of the CPU 46, and the like. The input/output port 52 is connected to a probe pin 34 via a multiplexer 36, a display device 42,
A storage device 44 and the like are connected. bus line 5
4 includes address bus lines, data bus lines, control bus lines, etc. for connecting these, and is also coupled to peripheral devices. Next, the operation of this embodiment will be explained. FIG. 3 is a flowchart consisting of steps P1 to P14 showing an example of a component and probe pin contact state determination processing program. To run this program, first, at P1, make the initial settings necessary to automatically inspect the quality of each component itself and the contact status of each probe pin. For example, select the measurement mode depending on the component: R for resistance measurement, C for capacitance measurement, L for inductance measurement, D for diode characteristic measurement, Z〓 for Zener voltage measurement, and Z〓 for short circuit inspection measurement. A mode such as S is used. Next, go to P2,
Step number A is set to 1 in order to automatically inspect the quality of each part. Next go to P3 and step A
Determine whether or not exceeds the maximum step. YES
In the case of , all the inspections for each component mounted on the mounting board have been completed, so go to P4.
P4 ends program execution. If NO, go to P5. In P5, it is determined whether the result of inspecting the quality of the parts corresponding to step A is GOOD.
If YES, the parts in step A are judged to be good, so go to P6. At P6, 1 is added to step number A, a new step number A is set, and the process returns to P3. In this way, P3, P5,
While repeating each step in P6, each part is inspected for quality. Please note that all steps are
If it is determined to be GOOD, the mounted board is considered to be a good board and the inspection ends. If the test result becomes NG in the process of P5 and it is judged as NO, the process goes to P7. In this way, NO judgment is made when the measurement mode is R and OVER or HIGH.
In case of UND. or LOW in C, in case of L
For OVER or HIGH, for NO.D for D,
For Z〓, it is HIGH or OVER, and for S, it is OPEN. In addition, OVER is when the test result exceeds the test range of the set range, and HIGH is LOW when the test result is outside the set upper limit.
is when the test result is outside the set lower limit,
UND. is when the test result is below the test range of the set range, NO.D is when the test result does not show the saturation characteristics of the diode, OPEN is the resistance value that is higher than the set threshold value. These judgments are made at each time, and in both cases, it is impossible to determine whether there is a contact failure or a component failure. In P7, specify the number of the H-PIN (probe pin on the signal source side) connected to the component in step A. Normally, when measuring the electrical characteristics of a component, probe pins are connected to both ends of the component, but if the component has polarity, the H (signal source side) and L (measurement side) ends are considered.
Next, go to P8. At P8, the subprogram for displaying contact failure probe pins shown in FIG. 4 is entered. First, in P81, it is determined whether the H-PIN with the designated number has already been tested for contact status. If YES, P82
go to At P82, since the H-PIN contact status is good, the part is determined to be defective and the process returns to this program. If NO, go to P83. At P83, set step number B to 1 and set count number C to 0. Note that C indicates the number of defective components that share the designated signal H-PIN. Next, go to P84. At P84, it is determined whether step B exceeds the maximum step.
If NO, go to P85. At P85, it is determined whether the part in step B is the part whose designated H-PIN number is used for measurement. If NO, go to P86. At P86, add 1 to step number B, set a new B, and return to P84. In this way, P84, P85,
Repeat each step of P86 until YES is determined in P85. If YES on P85, that is, the specified number H-
Each time step B using a PIN is reached, the process goes to P87. In P87, the quality of the part using the H-PIN of the specified number is inspected, and it is determined whether there is an NG in step B. If YES, go to P88. At P88, add 1 to the count number C, set a new C, and go to P86. If NO on P87, go to P89. At P89, it is determined that the contact state of the H-PIN is good for the component with step number A, which was previously determined to be NO at P5. Next, go to P90. P90 determines that the part is defective and returns to this program. Because,
This is because if the judgment for other parts that share the H-PIN with the specified number is GOOD, that H-PIN does not have a poor contact. If the judgment is YES in the previous P84, go to P91.
In P91, it is determined whether the count number C is 2 or more. YES
If so, go to P92. On P92, the specified number H-PIN
is determined to be a poor contact and returns to this program. NO.
If so, go to P89. This is because unless there are two or more defective components that are connected to the same independent pattern and share the designated probe pin, it cannot be determined that the designated probe pin has a contact failure. Since there is no information on other parts connected to the independent pattern and it is not possible to determine whether there is a defect in the part itself or a poor contact with the probe pin, it is determined at P90 that the part is defective. Note that later, using a general tester or the like, it is confirmed whether the part is really defective. When you return to this program, go to P9. At P9, it is determined whether the H-PIN of the designated number whose contact status was checked earlier has a poor contact. If YES, go to P10. At P10, the specified H-PIN number is displayed as contact failure on the screen or recorded on the recording paper. Then or at P9 NO
In this case, both go to P11. In P11, the L-PIN connected to the parts of step A
(Measurement side probe pin) number. Next, go to P12. At P12, the subprogram again enters the contact failure probe pin display processing subprogram, and this time, the contact status of the designated number L-PIN is checked in the same way. After that, return to this program and go to P13. In P13, it is determined whether the L-PIN of the specified number whose contact status was checked earlier has a poor contact.
If YES, go to P14. At P14, the specified L-PIN number is displayed as contact failure on the screen or recorded on the recording paper. After that, or if NO at P13, both go to P6. In this way, the process is repeated for all steps, and it is automatically determined whether the NG is due to a defect in the component itself or a poor contact with the probe pin. Effects of the Invention According to the present invention as described above, when a defect is determined as a result of the inspection of the quality of each component mounted on a mounting board to be inspected, it is possible to determine whether the defect is due to a defect in the component itself, or whether the probe pin contact It is possible to automatically determine whether the problem is caused by a defect, so by quickly determining whether the contact state of the probe pin is good or not,
Speeding up inspection can be achieved. Furthermore, since there is no intervention of human judgment, there are no unstable factors and the test can be performed accurately.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an in-circuit tester having a probe pin contact failure determination function according to the present invention. FIG. 2 is a block diagram showing an in-circuit tester having a probe pin contact failure determination function to which the present invention is applied. FIG. 3 is a flowchart showing a component and probe pin contact state determination processing program, and FIG. 4 is a flowchart showing a contact failure probe pin display processing subprogram. FIG. 5 is a layout diagram showing a state in which a mounting board to be tested is fixed by a press on a fixture in an in-circuit tester. FIG. 6 is a bottom view showing an example of a single-sided printed circuit board before parts are mounted. 34... Probe pin, 40... Device equipped with CPU, 42... Display device, 44... Recording device, 5
6... In-circuit tester, 58... Means for inspecting components using designated pins, 60... Means for counting the number of defective parts, 62... Means for determining defective contact pins.

Claims (1)

[Claims] 1. Fix the mounting board to be tested on the fixture, and measure the electrical characteristics of each component by touching each probe pin attached to the fixture to each measurement land to which each component mounted on the board connects. , to the in-circuit tester that inspects the quality of each component, specify the probe pin used to measure the component determined to be defective through those inspections, and then specify the probe pin used to measure the component that is determined to be defective. A component inspection means using designated pins measures the electrical characteristics of the component and inspects the quality of the component; a defective component number counting means counts the number of defective components that share the designated probe pin; What is claimed is: 1. An in-circuit tester having a probe pin contact failure determination function, comprising contact failure pin determination means for determining that a designated probe pin has a contact failure when the specified probe pin reaches a value of 1.